Soldering



UNITED STATES PATENT OFFICE.

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This 'invention relates to soldering and, more especially, to a method o f, and a com position adapted for use in Joining metal parts, it being among the ob ects of th1s m- 5 vention to produce a simple and economical method of joining metal parts and a composition for use in such method. I Hitherto, soldering has generall been performed by first cleanin the sur aces to be joined by means of suitable substances, such as fluxes, to remove dirt and oxidized portions of metal and then' meltin the soldering material upon the parts to be joined. Such process has several disadvantages,-

l5 requiring considerable skill to properly perform the same, and the joints produced 0 ten lacking uniformity,-these being overcome by the present invention.

I have discovered that metallic joints may be made between metal parts by means of a metal, preferably having a lower melting point, being deposited from an anh drous, fusible, and easily reducible metallic salt. The making of such metallic joints may be facilitated by adding to p the anh drous, fusible, and easily reducible metal ic salt other anhydrous salts or organic compounds which will alter the fusibihty, volatility, or reducing power of the salt and which will have 'i icleaning action on, and revent the oxidization of, the metallic sur aces to be joined.

Many substances are suitable for carrying out my method, among which are compounds including ammonium halogen salts in combination with anhydrous halides of tin, zinc, aluminum, bismuth, antimony, copper, chromium, cadmium, etc.

An example of the formation of one of the 40 above compositions, which consists of an anhydrous, easily reducible metal halide and avolatile fluxing material, is as follows :-ap proximately theoretical proportions of stannous chloride (SnC1 and ammonium chloride (NH,C1) are fused together to produce the double-salt ammonium stanno-chloride [(NH ),SnCl,]. This substance may be prepared in other well known manners. If desired, other constituents, which reduce the volatility or increase the ease of reduction of the salt, such as anhydrous hydrochloric acid, ammonium chloride, or resins, may be added. The production of soldered joints by disadvantages lemme.

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means of compositions of the above character is very simple. For instance, in order to weld aluminum sheets together, it is merely necessary to fuse a compound, such as am-. monium stanno-chloride, between the sheets of metal, and .press the sheets together, thus uniting the same. tion between the aluminum and the tin in the compound whereby tin is liberated to form the joint, the aluminum replacing the tin in the combination.

In the use of such compositions, the halide of a metal or metals WhlCh stands lower in the electromotive series than does the metal to be soldered, should be used. As a result, the metal to,be soldered liberates and deposits some of the metal from the salt and the metal so deposited acts as the bond. On account of the formation of the metal from one of its compounds at the point where it is to be used, it is more active than the metal formerl used in the free state, and is much more 0 osely held by the metal bein soldered which generally alloys with the eposited metal.

The term freely liberated metal used in the claims is intended to cover a metal which is obtained from a compoundthei-eof in the same operation in which it is applied as solder. In other words, the term covers metal which is reduced to the metallic state substantially. at the time it is used.

Having thus fully described In vention, what I claim as new an desire to secure by Letters Patent is 1. A soldering composition for metals above tin in the electromotive series comprising an inorganic salt of tin and an ammonium halide salt in which at least a part of said salts is combined to form a double salt that is reducible below the melting point of the soldered metal.

2. A soldering composition for metals above tin on the electromotive series comprising an anhydrous stanno-halide and an ammonium halogen salt, said composition be- The heat induces a rewsaid in- 4. A soldering composition for metals above tin in the electromotive series comprising a plurality of inorganic-metal-salt components inclu ing ammonium chloride and an anhydrous stanno-halide double salt, said double salt being fusible and reducible by the soldered metal below the melting point of said metal and being such that the unrediu-ible components thereof and the unreducible products of reduction are volatile at said soldering temperature.

5. A soldering composition for metals above tin in the electromotive series comprising a plurality of one or more easily reducible inorganic metal salts, one of which is a double salt of tin and a halide salt, said double salt being fusible and reducible below'the melting point of the metal to be soldered and the remainder being volatile at soldering tern eratures.

6. A solid usible composition for soldering metals comprising an inorganic metal halide and a non-reducing, flux for controlling the fusion temperature of the composition so that the metal halide will fuse below the melting point of the metal to be soldered, said metal halide being reduced to the metallic state by the metal to be soldered.

7. A solid fusible composition for soldering metals comprising a plurality of inorganic metallic halides to which ammonium .chloride has been added to control the fusion temperature of the composition so that the metal halide will fuse below the meltin" point of the metal to be soldered, said meta halides being reduced to the metallic state by the metal to be soldered.

In testimony whereof, I have hereunto subscribed my name this 26th day of July, 1920.

HENRY C. P. WEBER. 

